40 C.F.R. § 131.4 : Protection of Environment — ENVIRONMENTAL PROTECTION AGENCY — WATER PROGRAMS — WATER QUALITY STANDARDS — GENERAL PROVISIONS — State authority

(a) States (as defined in §131.3 ) are responsible for reviewing, establishing, and revising water quality standards. As recognized by section 510 of the Clean Water Act, States may develop water quality standards more stringent than required by this regulation. Consistent with section 101(g) and 518(a) of the Clean Water Act, water quality standards shall not be construed to supersede or abrogate rights to quantities of water.
(b) States (as defined in §131.3 ) may issue certifications pursuant to the requirements of Clean Water Act section 401. Revisions adopted by States shall be applicable for use in issuing State certifications consistent with the provisions of §131.21(c).
(c) Where EPA determines that a Tribe is eligible to the same extent as a State for purposes of water quality standards, the Tribe likewise is eligible to the same extent as a State for purposes of certifications conducted under Clean Water Act section 401.

40 C.F.R. §131.4

56 FR 64893, 12/12/1991, as amended at 59 FR 64344, 12/14/1994